Reducing cadmium uptake without compromising nitrogen uptake, photosynthesis, or yield in low-Cd hybrid rice

Abstract

Context

The presence of cadmium (Cd) in rice fields poses a significant threat to both rice production and human health. The low-Cd hybrid rice variety Zhenliangyou 8612 (L-Cd ZLY8612), developed through the mutation of the OsNRAMP5 gene, exhibits significantly lower Cd uptake. However, the impacts of this mutation on nitrogen (N) uptake, photosynthetic efficiency, and grain yield remain unclear.

Method

A two-year field experiment, along with a pot experiment, was conducted using Cd-contaminated soils and four different nitrogen treatments. Key parameters, including Cd uptake, photosynthesis, biomass, and yield, were measured, alongside ¹⁵N isotope tracking to assess N uptake and utilization efficiency.

Results

The average Cd concentration in L-Cd ZLY8612 grain was 73.4 % lower than that in ZLY8612 across two years of field experiments. Despite the OsNRAMP5 mutation, N uptake and utilization in L-Cd ZLY8612 were comparable to ZLY8612, with no significant differences in photosynthetic traits, dry matter accumulation, or grain yield. These findings suggest that L-Cd ZLY8612 can effectively reduce Cd accumulation without compromising N uptake or yield.

Conclusions

L-Cd ZLY8612 effectively reduces Cd uptake without compromising N uptake or yield performance. The cultivation of low-Cd rice varieties such as L-Cd ZLY8612 presents a viable strategy for mitigating soil Cd contamination, while ensuring stable rice production.